The results by Huang and colleagues demonstrated that treatment of prostate cancer cell lines PC3, DU145, and BH1 with sodium butyrate (NaBu), a histone deacetylase (HDAC) inhibitor, increased the expression of CPA4 mRNA in a p21 WAF1/CIP1 transactivation-dependent manner [7]. The gene discussed is CPA4; the disease is prostate carcinoma.